Systems that deliver certain drugs to a patient (e.g., targeted to a particular tissue or cell type or targeted to a specific diseased tissue but not normal tissue), or that control release of drugs has long been recognized as beneficial. For example, therapeutics that include an active drug and that are capable of locating in a particular tissue or cell type e.g., a specific diseased tissue, may reduce the amount of the drug in tissues of the body that do not require treatment. This is particularly important when treating a condition such as cancer where it is desirable that a cytotoxic dose of the drug is delivered to cancer cells without killing the surrounding non-cancerous tissue. Further, such therapeutics may reduce the undesirable and sometimes life threatening side effects common in anticancer therapy. For example, nanoparticle therapeutics may, due the small size, evade recognition within the body allowing for targeted and controlled delivery while e.g., remaining stable for an effective amount of time.
Therapeutics that offer such therapy and/or controlled release and/or targeted therapy also must be able to deliver an effective amount of drug. It can be a challenge to prepare nanoparticle systems that have an appropriate amount of drug associated each nanoparticle, while keeping the size of the nanoparticles small enough to have advantageous delivery properties. For example, while it is desirable to load a nanoparticle with a high quantity of therapeutic agent, nanoparticle preparations that use a drug load that is too high will result in nanoparticles that are too large for practical therapeutic use. Further, it may be desirable for therapeutic nanoparticles to remain stable so as to e.g. substantially limit rapid or immediate release of the therapeutic agent.
Accordingly, a need exists for new nanoparticle formulations and methods of making such nanoparticles and compositions, that can deliver therapeutic levels of drugs to treat diseases such as cancer, while also reducing patient side effects.